S&W Brazilain Contract Fail to Fire on 6th round in Double Action

This revolver was giving me light primer strikes in Double Action. I installed a Cylinder and Slide .002 end shake bearing and now it will fire 5 rounds DA then it will not fire DA until I fire one round SA. Once I do fire SA it will fire again. It does this with both factory loads and reloads are are more or less duplicates of factory. It also does this with a variety of moon and half moon clips.

I've also installed a new wolf main spring and put a shim (fired primer) over the set screw.

Anyone got thoughts on this?

Have you measured how much end shake remains after installing the "bearing"/shim? Also what's the actual head clearance (i.e. gap between the end of the case and the recoil shield with the case fully forward.) How's the timing? Does the firing pin fully protrude through the recoil shield when the trigger is pulled? I'm not sure that the modern mainspring is the best choice- put the original one back in, unless there's something wrong with it. That's just stuff that occurred to me for starters, there's plenty else, but 15-30 seconds "hands-on" is apt to turn into days worth of posts on-line. It might be best to find someone local who really knows vintage Smith and Wessons if you can!

Quite the involved first post! Welcome aboard.

:wave:

Sometimes the mainspring will knucke. That is to say the top end where the claws are will actually bend a bit toward the hammer. This will decrease the spring tension. I've had it happen to brand new springs, usually when single actioning a revolver. Also if you load your own use Federal 150 primers and this problem will likely end. Like J says, if I had it in my hands for a minute this would be over. Also remember, this revelver was made for which contract? 1937? Mine was and it had seen a better life years ago. I bought a 625 and sold the 1917. No more problems.

Since you installed an end shake bearing,can you still move the cylinder forward and backward?

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Originally Posted by Bruce McAskill

Since you installed an end shake bearing,can you still move the cylinder forward and backward?

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very slightly - I tried a second bearing but it was too snug

Get some feeler gages at least to check the head clearance.

I'm still pretty sure that the newer model mainsprings aren't compatible with the pre- WWII revolvers. I think the mainspring length changed enough to mess with the proper hammer swing. See browningautorifle's post above. If it is wrong the "feel" when bring the hammer to full cock won't be uniform. I'm sure I've encountered this before, but don't remember if the old spring is longer or shorter. Also if the spring hits a grip screw it'll mess things up.

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Originally Posted by jmoore

Get some feeler gages at least to check the head clearance.

I'm still pretty sure that the newer model mainsprings aren't compatible with the pre- WWII revolvers. I think the mainspring length changed enough to mess with the proper hammer swing. See browningautorifle's post above. If it is wrong the "feel" when bring the hammer to full cock won't be uniform. I'm sure I've encountered this before, but don't remember if the old spring is longer or shorter. Also if the spring hits a grip screw it'll mess things up.

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put the old spring back in - left the fired primer as a shim over the strain screw and perfect

all primers have even and authoritative primer strikes

Off to the range with ya!

Parts interchange on Smiths of varying vintages needs it's own spreadsheet. It's even tricky on the numbered and "dashed" variations.

A range report WOULD be most welcome!

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Originally Posted by jmoore

Parts interchange on Smiths of varying vintages needs it's own spreadsheet. It's even tricky on the numbered and "dashed" variations.

A range report WOULD be most welcome!

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Some old pics

https://www.milsurps.com/images/impo...5335698c-1.jpg

https://www.milsurps.com/images/impo...4a4e564c-1.jpg

I put 48 rounds of 255 gr cast reloads through it last night w/o a hitch. It shoots straighter than I can hold it still

Exellent. I was heart broken when mine turned out to be a plug. I wanted one for years. Of course now they've all dried up. Like I say, the 625 works like magic.

Heh, 625s have been the misfiring champions for me. Have had two that just wouldn't do right- both frame mounted firing pin variants. Upped spring tension, added Ron Powers shim bearings, made a longer firing pin, all to no avail. Too bad too, because they cost valuable time and points in matches after I thought they were sorted. Now that I don't shoot competition, I have a "Jerry Miculek" 625 that works fine. Still, the old M1917s and such are good gear. I particularly like the .455s. But why do the M1917s recoil so much "harder"?

Because they are so much lighter in the front end.

I mean harder than .455s or 44spl in revolvers of the same vintage. Maybe it's the smooth grips? Or possibly the fact that I tend to shoot them fast and DA? I just know that my hand and eyes tell me that it takes more work to get back on target. Muscle memory- It 's a weird thing sometimes (and altogether subjective)!

I've never shot a 1917 in 455 or 44 spl. Maybe the grips don't help. No grip there. I shoot revolver DA always too, that's how they were meant to be shot.

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Originally Posted by browningautorifle

I've never shot a 1917 in 455 or 44 spl.

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Technically, the 1917s (U.S. Military issued .45 ACP revolvers) are a variant of the pre-WWII large frame hand ejectors, of which there are quite a few calibers- .38 Spl. (AKA 38-44), .44 Spl., .45ACP/AR, .455, .45 Colt, plus a few really odd ducks, and later, the .357 Magnum. Not as wide a range of calibers as the Colt New Service, which also has a "M1917" variant, but enough to be entertaining for collectors.

Although the Brazilian contract revolvers are often thrown into the same bucket as M1917s, they have their own production quirks, esp, those later on in the run.

THe pre-WWII revolvers are generally quite smooth in operation, but I can't seem to get them to work when the trigger pulls are lowered to what is common now. The internal geometry seems to have changed just after the end of WWII, but finding good late 1930's examples is more difficult than examples made earlier or later, so just exactly when the major internal changes started I don't know (aside from the evolution of the internal safeties, which is well documented). My favorite "vintage" Smiths from an "action" standpoint seem to be those built from about 1947 through 1955. The high point being roughly 1949-50.

Example: Wouldn't I love to get a model 1950 four inch...

I was told on the S&W forum that the year 1948 was the change over to the newer internals on all of the S&W line. The 1937 is kind of an odd duck so to speak in that S&W made new frames for the first half of the Brazilian contact and delivered these. But with the war coming S&W did not finish the contract and placed it on hold. The second half was completed in 1946 and the frames used were from US government or S&W storage and were stamped with the US acceptance marks. These frames have the rounded area of the rear sight like the 1917, while the first ones have a square shape.

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Originally Posted by browningautorifle

Example: Wouldn't I love to get a model 1950 four inch...

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Some Bubba hacksawed the end off a .45 acp converted .455. Cut it crooked to boot.

So, after 5-6 years of having it lie about, I went and cut it "square" about a week ago. Now about 3 3/8". Having evil thoughts of making a round butt out of it and trying a titanium cylinder that's also spare- it seems unlikely to work w/o a boatload of tinkering though.

https://www.milsurps.com/images/impo...stuff005-4.jpg

Now to find the ruptured M1917 barrel, as I think the sight is salvagable.

I'd round butt that in a heart beat. I'm sure you can organize a round-ish front sight and a set of N frame Hogue grips to finish it off. Maybe a bead blast and blue. New carry gun. What a handful with Glazer safety slugs and full moon clips.